This invention relates to fluidised bed combustion apparatus and to furnaces and incinerators embodying such equipment. The invention is particularly concerned with provision of large capacity fluidised bed combustion apparatus.
It has been proposed to provide fluidised bed combustion apparatus in which a fluidised bed of granular material is supported in a housing on an air diffuser bed support. In such an arrangement fuel or waste material to be burnt, either to raise heat or for disposal purposes, is fed into the fluidised bed to be burnt therein, the oxygen for combustion coming at least in part and usually entirely from air and into the bed from the diffuser support to fluidise the bed. The diffuser is in some cases arranged to slope from one side of the bed to the other, and the supply of fluidising air to the various areas of the diffuser being selectively controlled to cause the bed materials to circulate about a generally horizontal axis extending across the slope of the diffuser.
It is an object of the present invention to provide a large capacity fluidised bed combuster embodying such principles.
It is a further object to provide a large capacity fluidised bed combuster which is flexible in operation, and the heat output of which can be raised to meet widely varying demands for heat, while still maintaining efficient and effective combustion conditions within the combuster. In the operation of circulating fluidised beds, it is costly and difficult to maintain the circulation of the bed and effective combustion conditions in a large bed when it is desired to burn only an amount of fuel which is small in comparison to the normal capacity of the bed, to produce a small quantity of heat when the demand is below the normal capacity of the plant in which the bed is operating.